Circuit cards residing in a card rack of, for example, a NEMA TS2 traffic signal controller are configured for different types of traffic detection. Each card generally has up to four contact closure outputs for communicating with the traffic signal controller. However, it is often necessary to increase the output of each card to more than four outputs. Accordingly, what is desired is a system and method for expanding the output of each card without having to redesign the card. What is also desired is a modular system which allows the expansion of contact closure outputs without additional physical circuit cards to be added to the system.